The present invention relates to a technique for facilitating the alignment or positioning of an antenna adaptable for receiving transmitted signals.
In an analog broadcasting system (such as that associated with an NTSC TV system), analog television signals may be transmitted and received by a number of television receivers with the use of respective antennas. Each of such antennas may be aligned by moving or rotating the same until an acceptable picture is displayed on the respective television receiver. In such aligning of an antenna, the picture displayed on the television receiver may gradually change as the respective reception antenna is moved or rotated. As a result, the optimum or acceptable orientation or alignment of the antenna may be easily found.
In a digital television (DTV) broadcasting system, broadcasted DTV signals may be transmitted by way of a satellite or other type of relaying device(s) for reception by a number of television receivers with the use of antennas. Such broadcasted DTV signals may enable clearer pictures and sound to be produced by the television receivers as compared to those obtained from broadcasted analog NTSC television signals. However, in a DTV broadcasting system, it may be difficult to align an antenna so as to properly receive the broadcasted television signals. That is, DTV broadcasting may provide an all-or-nothing arrangement in which a television receiver may either properly receive a picture or may receive nothing at all. As such, there may be no "in-between" positions in which a somewhat acceptable/unacceptable picture is received, unlike in an analog NTSC broadcasting system. In other words, in DTV reception, decoded pictures may be obtained only when the antenna is aligned so as to be orientated within a relatively small angular range (such as +/-2.5 degrees) of the proper angular position. If the antenna is orientated so as to be at the end of the receivable angular span (which is a critical point), reception may become unstable with a relatively small movement of the antenna. That is, an acceptable picture may suddenly be displayed when the antenna is orientated within the small acceptable angular range and may suddenly disappear when the antenna is orientated so as to be outside the small acceptable angular range. As such, it may be difficult to align the antenna.
During the installation of an antenna for receiving broadcasted DTV signals, a so-called antenna meter may be utilized. Such antenna meter or antenna alignment value may be produced from an error rate of a received signal by a digital satellite receiver and may be displayed on a display unit. As an example, such antenna alignment value may lie within a range of 0 to 100 and may be presented in a bar format on a display 10, as shown in FIG. 6.
By observing the antenna alignment value, an installer is provided with an indication as to whether the current orientation of the antenna is acceptable or not. However, because the acceptable angular span is relatively narrow as previously described, the error rate or antenna alignment value may reach a limit on the bar display with only a relatively small angular movement of the antenna. Upon reaching such limit, the antenna alignment value may remain there until the antenna is moved so as to be orientated within the relatively narrow acceptable angular range.
Thus, the antenna alignment value may not gradually change as the antenna is moved or rotated. Accordingly, proper aligning or pointing of an antenna may be very difficult even with the use of the antenna meter.
Additionally, it may be desirable to receive broadcasted DTV signals which are transmitted in different directions. In such situation, the antenna needs to be aligned or positioned so as to receive the desired signals. As is to be appreciated, such positioning of the antenna may be more difficult than the above-described situation in which signals are transmitted in one direction.